Nozzle construction



May 1, 1962 Filed. Nov. 21, 1960 C. M. CZARNECKI NOZZLE CONSTRUCTION 2Sheets-Sheet 1 INVENTOR. (AS/MB? M. ('ZA/FA HK/ WMQM May 1, 1962 c. M.CZARNECKI NOZZLE CONSTRUCTION 2 Sheets-Sheet 2 Filed NOV. 21, 1960 MKRNAQl 4 hQ \Q SQ J NQ INVENTOR. (AS/NEE M. CZAENETK/ WW 3,932,279 NOZZLECGNSTRUCTION Casimer M. Czarnecki, New Hope, Pa, assignor to EddingtonMetal Specialty Company, Eddington, Pan, a copartnership Filed Nov. 21,1960, Ser. No. 70,538 6 Claims. (Cl. 239-464) This invention relatesgenerally to nozzles, and is especially concerned with improvements inmeteringliquidspray nozzles.

While the device of the instant invention has been primarily developedfor metering atomized fuel into the combustion chamber of a prime mover,and will be illustrated and described hereinafter with referencethereto, it is appreciated that the instant invention is capable of manyvaried applications all of which are intended to be comprehended herein.

As is well-known, in different types of present-day engines, such as gasturbines and jet engines, it is desirable or essential that the rate offlow of fuel fed to the combustion chamber be accurately controlled ormetered. Toward thisend, it has heretofore been necessary to providefuel nozzles of relatively complex and extremely precise construction,frequently requiring tolerances of .60010 inch, or less. Of course,these prior constructions were extremely expensive, necessarilyinvolving considerable machining, including grinding. Further, even whenprior fuel nozzles were manufactured to such tolerances with allpossible care, the finished product was often unsatisfactory, say byuncontrollable distortion, or the like.

It is, therefore, one object of the present invention to provide a fuelspray nozzle which is of greatly simplified construction, employingconsiderably less parts than heretofore required, and wherein the needfor close manufacturing tolerances is obviated, to eliminate precisiongrinding in manufacture and distortion in assembly and use.

Also required of such fuel nozzles is a wide range of flow rates along aspecified curve, and proper atomization of the fuel throughout the fiowrange. In order to achieve this desiderata, the prior-art devicesnecessarily employed separate lowand high-capacity flow passages, andusually required means for closing the high-capacity flow passage in thelow-flow range.

It is another object of the present invention to provide a fuel spraynozzle of the type described, which is adapted to produce a properlyatomized discharge cone throughout a wide flow range along a specifiedflow curve, and wherein the same passageways are employed throughout theentire flow range.

It is still a further object of the present invention to provide aliquid-spray nozzle having the advantageous characteristics mentioned,which is extremely simple in construction, durable and reliablethroughout a long useful life, and which can be more economicallymanufactured for sale at a reasonable price.

Other objects of the present invention will become apparent upon readingthe following specification and referring to the accompanying drawings,which form a material part of this disclosure.

The invention accordingly consists in the features of construction,combinations of elements, and arrangements of parts, which will beexemplified in the construction hereinafter described, and of which thescope will be indicated by the appended claims.

In the drawings:

FIGURE 1 is a longitudinal sectional viewshowinga liquid-spray nozzle ofthe present invention, illustrating the same in closed condition;

FIGURE 2 is a fragmentary elevational view showing the construction ofFIGURE 1 in an open condition;

FIGURE 3 is a longitudinal sectional view showing a slightly modifiedconstruction of nozzle according to the teachings of the presentinvention, illustrating closed condition; and

FIGURE 4 is a fragmentary eievational view showing the construction ofFIGURE 3 in an open condition, and partly in section for clarity ofunderstanding.

Referring now more particularly to the drawings, and specifically toFIGURES l and 2 thereof, a nozzle is there generally designated 10 andincludes a generally cylindrical outer shell 11 having its forwardendclosed by a front-end wall 12 which is provided with a central or axialthrough opening or discharge orifice 13. The rearward end of the outershell 11, the left-hand end as seen in FIGURE l,'is open.

The cylindrical outer shell 11 is provided interiorly in its forwardregion with an interior space or chamber 15 of generally cylindricalconfiguration, opening forwardly through the orifice 13, and bounded onits forward end by a generally conical internal front wall 16 axiallyconverging to the orifice. The internal spaceor chamber 15 is furtherbounded by a generally cylindrical internal wall 17 extending coaxiallywith and rearward from the radially outer circumferential extremity ofthe internal wall surface 16. The cylindrical side wall 17 terminatesrearwardly at an internal rearwardly facing annular shoulder 18 defininga circumferentially enlarged chamber region 19. That is, the internalrearwardly facing annular shoulder 18 is formed in the outer shell 11,extending radially outward from the rearward edge or corner of thecylindrical internal side surface 17 and terminating at a cylindricalinternal side surface 20 of greater diameter than the cylindricalsurface 17 From the internal cylindrical surface 20, the outer shell 11flares rearwardly, being formed with a conical surface 21 of rearwardlyincreasing internal dimension. Rearwardly of the internal conicalsurface 21, the outer shell 11 is internally enlarged, as at 22, andprovided in the enlarged region 22 with internal screw threads 23.Rearward of the screw threads 23 the outer shell 11 is further enlarged,as in the region 24, andthere provided with additional internal screwthreads 25. The rearward end of the outer shell 11 may remain open; and,an annular extension collar 26 may be provided on the outer shell 11,medially between the ends thereof, as for mounting the outer shell in anengine combustion chamber.

Axially received within the cylindrical outer shell 11 is a generallycylindrical inner shell 30. The inner shell 30 is located concentricallyor coaxially within the outer shell 11, and is formed with an internalaxial through opening or bore 31. The inner shell 30 extendsforwardlyinto the interior of the outer shell 11, terminating at its forward endin an annular forwardly facing end surface 32, which surface isadvantageously generally fiat and normal to the axis of the inner shell.It will be observed that the internal diameter of the through opening 31is less than the internal diameter of the chamber side wall 17, so thatthe radially inner edge of the inner-sleeve forward end surface 32 islocated radially inward of the chamber side Wall 17 and the radiallyinner edge of the annular rearwardly facing chamber surface 18. Further,the innersleeve end surface 32 intersects with the surface of bore 31 atsubstantially a right angle. The inner-shell forward end surface 32 maybe considered as an internal, annular forwardly facing shoulder andcombines with the rearwardly facing shoulder 18 and circumferential sidewall 20 to define an internal annular groove or chamber communicatingwith the main cylindrical region of chamber 15.

3 Formed exteriorly of the inner cylindrical shell 36 is a generallycylindrical external surface 33 extending rearward from the forward endsurface 32 and terminating at a rearwardly flaring conical externalsurface 34. The cylindrical external surface 33 engages slidably withinthe cylindrical internal surface 20, while the conical external surface34 is in forwardly abutting engagement with the conical internal surface21.

Rearward of the external conical surface 34, the inner cylindrical shell30 is provided with external screw threads 35 in threaded engagementwith the internal screw threads 23 of the outer shell 11. Rearward ofthe screw threads 35 there is provided exteriorly on the inner shell 30an annular circumferential shoulder or collar 36 which is received inspaced relation within the enlarged region 24 of the outer shell 11.Rearward of the collar 36, the inner shell 30 is reduced to provide acylindrical external surface 37 extending rearward from the collar 36,and is further reduced at 38 to provide a cylindrical surface proximateto the annular end surface 39.

The outer shell 1-1 and inner shell 36 may be considered as combining todefine a generally cylindrical housing of the nozzle 14), wherein theforward internal space or region 15 defines a swirl chamber for fuelprior to discharge through the orifice 13, and the annular internalgroove 19 may be considered as a preliminary swirl chamber, as willappear more fully hereinafter.

A generally cylindrical piston sleeve is slidably engaged within thebore 31 of the inner housing shell 30, and generally designated 40.Located within the sleeve 40 is a piston core, generally designated 41.The sleeve 40 and core 41 combine to define a piston slidable in thehousing 11, 30.

More specifically, the sleeve 46 is formed with a central or axial,longitudinally extending through bore or opening 42, and is formedexternally with a circumferentially extending groove 43 located mediallybetween the forward and rearward ends of the sleeve. Extending inwardfrom the rearward end of the sleeve 40, longitudinally thereof, are aplurality of external, longitudinally extending grooves or slots 44which open forwardly into the circumferential groove 43. The grooves 44may be arranged at equally, circumferentially spaced locations about thesleeve 40, the material remaining between the slots 44 defininglongitudinally extending, radially projecting ribs 45. Forward of thecircumferential groove 43, the sleeve 40 is formed externally with aplurality of spaced, circumferentially arranged grooves 46, preferablyextending generally spirally or helically about the axis of the sleeveand terminating just short of the forward sleeve end 47. The annularsurface of the forward sleeve end 47 is preferably substantially flatand disposed in a plane normal to the axis of the sleeve. Thus, it willnow be appreciated that the sleeve 40 is slidable longitudinally withinthe inner housing shell 30, and that the slots 44, groove 43 and groovesor slots 46 combine with the internal surface of inner shell 30 todefine rearwardly opening fluid passageways, which passageways areadapted to communicate with the chambers 19 and 15 upon forward movementof the sleeve beyond the shoulder 32.

The core 41 includes an enlarged medial region 59 which may be force fitin the central bore 42 of the sleeve 49, spaced between the rear andfront ends of the latter. Extending rearward from the medial coreportion 50 is a reduced rearward extension 51, preferably terminatingshort of the rear sleeve end, while a forward extension 52 extends fromthe medial core portion forwardly to and terminating substantially flushwith the forward sleeve end 47. On the forward extension 52 of the core41, forward and exteriorly of the sleeve 40 is an enlargement or head53. The head 53 is of generally circular-outline configuration,extending radially beyond the sleeve 49, and includes a generallycylindrical rear pordegrees. The rear cylindrical head portion 54 is ofa diameter less than the internal diameter of chamber wall 17, andextending forwardly from the cylindrical portion is the conical,forwardly convergent head portion 53, which is provided centrally at itsforward end with an elongate, conical tip 56 adapted to enter in spacedrelation within the orifice 13. The entire core 41, including theportions 50, 51 and 52 received within the sleeve 40, and the headportions 53, 54 and 56 are all fixedly secured together, preferablybeing integrally formed.

It will now be appreciated that the rear surface 55 of the head 53 isadapted to conformably seat on the forwardly facing shoulder 32, amaximum of seating engagement therebetween being obtained by utilizationof the right-angle external corner on the inner edge of the shoulder,and the right-angle internal corner at the juncture of surface 55 withthe exterior of the sleeve 40. This seating engagement provides aneffective seal against the passage of fluid from the passageways 44, 43and 46 into the chambers 19 and 15, while opening such passageways tocommunication with the chambers upon forward movement of the sleeve 46and core 41 with its head 53. Thus, a highly effective seal is obtainedby seating engagement of the rear head surface 55 on the forwardlyfacing shoulder 32, without frictional or wedging engagementtherebetween. This permits unseating of the head from the shoulderwithout resistance for opening fluid communication and discharge of thenozzle at a precise pressure, as desired.

Thus, the sleeve 40 and core 41 combine to define a piston within thehousing 11, 30 movable forward from the illustrated, closed position.Circumposed about and extending rearward beyond the rear core portion 51is a tubular member or cap 60 which is anchored to the core 41 by atransverse pin 61 extending through the cap and rear core portion 51.The cap 60 extends rearward beyond the rear end of sleeve 40 and has itsrear end closed, as at 62, except for a central through opening 63. Aconnector element or rod 64 is provided on its forward end with anenlargement or head 65 received within the cap 60, and extends rearwardtherefrom through the opening 63. The forward end of connector rod 64 isthus retained within the cap 60, while the connector rod is of elongateconfiguration and provided on its rear end with an additionalenlargement or head 66. Spacedly circumposed about a forward region ofthe elongate connector rod 64 is an annular member or guide 67 whichseats on the rear end 39 of the inner housing shell 30. The guide member67 includes an annular forward flange 63 circumposed about the reducedinner-shell portion 38 to locate the guide axially of the housing 11,30, and also includes an annular rear flange 69 of a diameter less thanthe internal diameter of inner shell 30.

A rear annular member or guide 70 is Spacedly circumposed about therearward region of connector rod 64, just forward of rear-end head 66,and is provided with an annular forwardly extending flange 71 of adiameter approximately equal to that of flange 69. An annular retainer72 is circumposed about the connector rod 64, being interposed betweenthe rearward side of guide member 70 and the rear head 66 to preventrearward removal of the guide from the connector rod; and, suitableresilient means, say in the form of a coil compression spring 73 may beinterposed between the guides 67 and 70 to resil iently bias theconnector rod 64 rearward. That is, the helical coil compression spring73 may be circumposed about the rear flange 69 of the spring guide 67having its forward end in bearing engagement with the spring guide,

and the rear end of the compression spring may be circumposed about theforward flange 71 of the rear spring guide to insure proper axialcircumposition of the spring about the connector rod. Suitable spacerelements 75 may be engaged between the rear spring guide 70 and rear endof spring 73 to insure maintenance of the spring under propercompressive force. The spring 73, while in compression, is operativelyconnected through the rear spring guide 70, connector rod 64 and cap 60with the core 41 of piston 40, 41 to constantly resiliently urge theentire piston rearward. Further, the spring 73 is connected as notedabove more directly to the core 41 than the sleeve 40, to apply arearward force to the core and its head 53 in opposition to the forwardforce of fluid on the rear side of the piston, and specifically on therear Side of the piston sleeve 46. This action serves to moreeffectively insure maintenance of the rear head surface 55 in firmabutting engagement with the forward end surface 47 of the sleeve.

In addition, a generally cylindrical, open cage or strain er support 77is provided on its forward region with external screw threads '78 forthreaded engagement with the internal screw threads 25 of the outerhousing shell 11. That is, the forward end of the strainer cage orsupport 77 engages interiorly within the inner end of the outer shell11, in threaded connection therewith, and has its forward end in forwardabutting engagement with the rear side of collar 36. This serves toeffectively lock the inner housing shell 31} in position within theouter housing shell 11 and prevent disengagementof the surfaces 34 and21 even under high fluid pressure. Thus, the strainer support or cage 77serves as locking means for the inner housing shell 30.

A cylindrical strainer 80 is engaged exteriorly about the lockingstrainer support 77 and retained in position thereon by a cap 81, whichis in turn secured by a retaining ring 82.

In operation, fluid under pressure enters radially inward through thestrainer 86 and strainer support '77 to apply pressure on the rear sideof the piston 40, 41. The fluid passes into the passages 44, 43 and 46,applying forward pressure to the piston 4c, 41, against therearwardbiasing force of spring 73. The rearwardly facing effectivepressure area of the piston 40, 41, as well as the strength of spring'73, are selected so that unseating of the piston head 53 from theshoulder 3-2 occurs at a precisely desired pressure. Upon initialopening of the nozzle, as shown in FIGURE 2, a relatively low rate offluid flow is metered from the slots 46 into the swirl chamber 19, fromwhich it continues its helical motion through the main swirl chamber 15and out in an atomized conical form through the discharge orifice 13.The proportions of the piston, chambers and orifice of the instantconstruction are readily capable of selection and change to produce awide range of properly atomized fluid discharge along any desired flowcurve within wide limits.

Referring now to the embodiment of FIGURES 3 and 4, a nozzle is theregenerally designated 110 and includes a'generally cylindrical outerhousing shell 111 having its forward end closed by an end wall 112 whichis provided with an axially extending through aperture or dischargeorifice 113. The forward interior region 115 of the outer housing shell111 is of generally cylindrical configuration, having its forward endbounded by the interior, generally conical surface 115 of theouter-shell end wall 112. The internal conical wall surface 116converges axially toward the discharge orifice 113, being provided atthe juncture thereof wtih an annular conical valve-seat surface 114. Theforward region or chamber 115 of the outer shell 111 is further boundedby a generally cylindrical internal wall surface 117 extending rearwardfrom the rear, large end of the conical surface 116 and terminating at agenerally fiat, rearwardly facing annular surface or shoulder 118. Thatis, the cylindrical surface 117 extends rearward to intersect with theannular generally flat surface 118, which extends radially outward fromthe cylindrical surface and terminates in an internal cylindricalsurface of a diameter greaterthan the cylindrical surface 117. Thus, theinternal rearwardly facing shoulder 118 and cylindrical surface 129define an enlarged region 119 within the outer shell 111, correspondingto the enlarged region 19 of the first-described embodiment.

iroceeding rearward from the enlarged internal region 119, the outershell 111 is further internally enlarged at 122 by the formation of anannular, generally flat shoulder 121 intersecting with and extendingradially outward from the internal cylindrical wall 129. The internalregion 122 may be provided with a generally cylindrical land 123 spacedrearward from the shoulder or abutment wall 121.

Rearward of the enlarged region 122, beyond the rear end of thecylindrical land 123, the outer shell 111 is further enlarged in theregion 124, and there provided wtih internal screw'threads 125. Formounting the outer shell 111 in a combustion chamber, there may beformed circumferentially about the exterior of the outer shell amounting shoulder 126.

A generally cylindrical inner housing shell 131} extends 7 forwardthrough the rear open end of the outer housing shell 111 axially of thelatter. The inner shell 131i is formed with an axial through bore oropening 131, which terminates at the forward end 132 of the inner shell.The forward end 132 is defined by an annular, generally fiat surfacedisposed in a plane normal to the inner shell and in forward abuttingengagement with the internal rear- Wardly facing shoulder 121 of theouter shell 111. The forward end surface 132 of the inner shell is thusdisposed in facing spaced relation with respect to the rearwardly facinginternal outer-shell shoulder 118 and combines with the latter to definean internal annular groove or chamber of the enlarged region 119'. Theinternal diameter of the bore or opening 131 is preferably less thanthat of the internal cylindrical surface 117, so that the forwardinner-shell end surface 132 may be considered as an internal annularforwardly facing shoulder corresponding to the shoulder 32 of thefirst-described embodiment. Exteriorly, the inner shell 130 is ofcylindrical formation, as at 135 for snug force-fit engagement in theouter-shell region 122. The rearward external region of inner shell 13%is reduced, as at 137, which reduced region is provided with an annularexternal groove 138 proximate to and spaced forward from the rear end139 of the inner shell.

A generally cylindrical piston sleeve 14% is arranged longitudinally ofand slidably within the opening 131 of the inner shell 131 Fixed to thepiston sleeve 140 is a piston core 141, which core and sleeve combine todefine a main piston. The piston sleeve 140 is formed internally with athrough axial opening or bore 142, and is formed externally with acircumferentially extending outwardly opening groove 143. The pistonsleeve 140 is further formed with a plurality of longitudinal externalslots 144, located in circumferentially spaced relation about the sleeveeach extending inward through the rear sleeve end and opening into theannular groove 143. Formation of the slots 144 serves to define betweeneach adjacent pair of said slots a longitudinally extending external ribor fin 145. Extending forward from the annular groove 143, the pistonsleeve 140 is formed with a plurality of external helically or spirallyextending radially outwardly opening grooves 146, which-groovescommunicate at their rear ends with the annular groove 143 and terminateat their forward ends short of the forward end 147 of the piston sleeve.The forward sleeve end 147 may be substantially flat and located in aplane normal to the longitudinal axis of the sleeve. Thus, the pistonsleeve 14% may be substantially identical to the previously describedpiston sleeve 40 of FIGURES 1 and 2.

The core 141 includes a generally cylindrical body portion 15%conformably force fit in the forward region of the sleeve opening 142,and includes a reduced cylindrical rearward region 151 extending inspaced relation rearwardly through and beyond the rear end of the pistonsleeve 140. Preferably integrally formed on the forward end of the corebody 156 is an enlarged head 153 of forwardly convergent conicalformation and having a generally cylindrical rear portion 154 insurface- .abutting engagement with the forward-end surface 147 of thepiston sleeve 14%. That is, the rear surface 155 of the forward-endenlargement or head 153 is generally flat and disposed in a plane normalto the axis of sleeve 140, while the diameter of the cylindrical portion154 is greater than the diameter of bore 131, so that the head 153extends radially outward beyond the sleeve 14% for surface-seatingengagement with the forwardly facing inner-shell end surface or shoulder132. As in the first-described embodiment, the rear surface 155 of theenlargement or head 153 defines a substantially right angle at itsjuncture with the external surface of the piston sleeve 149, while theinternal surface of bore 131 and the end surface or shoulder 132 definea substantially right angle at their juncture, for maximum seatingengagement between the head 153 and shoulder 132.

The rear core portion 151 is formed internally with a generallycylindrical chamber 156 terminating at a front wall 157 rearward of thecore body 150 and opening rearward from the reduced rear core portion.Apertures or ports 153 are formed in the rear core portion 151 openingradially inward into the forward region of the chamber 156, while areduced cylindrical bore 159 is formed extending forward through the endwall 157, the core body 151} and opening forward through the forwardside of head 153. The piston bore 159 is axially located and may be of adiameter slightly larger than that of the orifice 113.

A closure or cap 168 is secured over the rear end of the rear coreportion 151, as by screw threads 174 and provided with a rearward axialextension 188. A connector cap 160 is engaged over the extension 159,and a pin 161 passed transversely through the extension and connectorcap to positively secure the same together. The connector cap 1&0 hasits rear end 162 closed except for a central opening 163 which receivesthe forward end of a connector rod 164. The connector rod is provided onits forward end interiorly of the connector cap with an enlarged head165, and provided on its rear end with an enlarged head 166.

An annular spring guide 167 is circumposed about and engaged over therear end of inner shell 130, having an annular rearwardly extendingflange 169. A rear, annular spring guide 17%, substantially identical tothe spring guide 70 of FIGURE 1, is arranged about the rear end ofconnector rod 154, and provided with a rod retainer 172, while a coilcompression spring 173 and spacer means 175 are interposed between thespring guides 167 .and 171 A strainer support 177, which may be the sameas strainer support 77 of FIGURE 1, is engaged into the rear open end ofouter housing shell 111 and provided with external threads 178 inthreaded engagement with the internal outer-shell threads 125. Theremainder of the strainer assembly, including a strainer proper andretaining means therefor are also provided in the same manner as FIGURE1, so that a detailed description thereof is not necessary.

interposed in the chamber 156 between the rear end of rear core portion151 and the closure cap 157 is a gasket 135. The gasket 185 serves toseal the rear end of the chamber 156 and may be provided with acentering boss 186 engageable in the rear end of the chamber to properlylocate the gasket. The gasket is further formed with a forward, axialprojection 187 located in concentrically spaced relation within thechamber 156.

Slidably received in the chamber 156 is a subpiston 1%. Specifically,the subpiston 1% is located rearward of the ports 158 and includes aforward reduced extension 191 passing slidably forward through the bore159 of the piston core 141. The piston 190 is formed in its rear endwith a generally cylindrical, centrally located recess 1% adapted toreceive the forward gasket extension 139, and an elongate hole orpassageway 193 extends forward from the recess 192 and opens through theforward end of the reduced subpiston extension 191. The forward end ofthe subpiston extension 191 may be provided with a bevel or chamfer 194shaped to conformably seat on the bevel 114 of the outer shell 111. Acoil compression spring 195 is axially arranged in the chamber 156,being circumposed about and guided by the gasket extension 187, havingits rearward end engaging the gasket boss 186, and its forward endextending into and in engagement within the recess 192 of the subpiston1913. Thus, the subpiston 19% is slidable forwardly and rearwardlyrelative to the main piston 14 0, 141, being movable rearwardly againstthe force of spring 195. i

In operation, at a preselected fluid pressure, as determined by theforce of spring 173 and the rearwardly facing effective pressure area ofpiston 140, 141, the latter piston will be urged forwardly to unseat therear surface of piston head 153 from shoulder 132 and thereby open thepassageways 144, 131 and 1 :6 to communication with the chambers 119 and115. To prevent the ineffective discharge of .an improperly atomizedspray, the subpiston 190 temporarily remains in its forwardmost positionclosing the orifice 113. However, just subsequent to unseating of thepiston head 153 from the shoulder 132, when the swirl chamber 11?, issufficiently full, the subpiston 19f retracts, to open the orifice 113and permit properly atomized spray discharge of fluid therethrough. Thisrearward movement of the subpiston 19 3 is automatically effected by thepressure of fluid entering into the chamber 157 through the openings 158forward of the enlarged part of the subpiston. T hat is, the pressure offluid to be discharged operates to move the subpiston 19G rearwardagainst the force of coil spring 195. The selection of effectivepressure area of the subpiston 19d, and the force of spring 1&5 is madein corresponding relation with the size of rearwardly facing effectivepressure area of the main piston 146, 141 and the strength of spring173, so that as the fluid pressure rises the main piston moves furtherforward and the subpiston further rearward away from the orifice tomaintain proper atomization and rate of flow in accordance with adesired curve. The subpiston 1% by its restriction of the discharge 113insures fine spray and a full discharge cone in the low range of fluidflow, i25nd is fully retracted rearward during the high rates of Thecentral bore 193 through the subpiston permits the free discharge of anyfluid which may leak into the chamber 156, so that any fluid in thechamber may not lock the subpiston or prevent full retraction thereof.

From the foregoing, it is seen that the present invention provides aspray nozzle which fully accomplishes its intended objects and iswell-adapted to meet practical conditions of manufacture and use.

Although the present invention has been described in some detail by wayof illustration and example for purposes of clarity of understanding, itis understood that certain changes and modifications may be made withinthe spirit of the invention and scope of the appended claims.

What is claimed is:

1. A nozzle construction comprising a generally cylindrical housinghaving a closed forward end provided with a discharge orifice, aninternal forwardly facing shoulder in said housing spaced from theforward housing end, a piston slidable in said housing having on itsforward side an enlarged head located between said shoulder and forwardhousing end and movable into and out of seating engagement with saidshoulder, said piston being provided with passage means communicatingbetween opposite sides of said piston when said piston head is out ofsaid seating engagement, said passage means being closed when saidpiston is in said seating engagement, resilient means operativelyconnected between said housing and piston to bias the latter rearwardand urge said piston head into said seating engagement, said resilientmeans being of a strength such that a desired piston pressure on therear side of said piston unseats said piston head and opens said passagemeans, a subpiston slidably mounted longitudinally of and within saidfirst-named piston and having its forward end extending beyond said headfor closing engagement with said orifice, said subpiston being formedwith a forwardly facing effective-pressure-area surface communicatingwith said passage means for effecting movement of said subpistonrelative to said first-named piston away from said orifice, andadditional resilient means operatively connected between saidfirst-named piston and subpiston for urging the latter forward towardclosing engagement with said orifice, said effective-pressure-areasurface being of a size and said additional resilient means of astrength to retain said subpiston in said closing engagement aftermovement of said first-named piston out of said seating engagement toinsure proper atomization of fluid upon discharge from said orifice.

2. A nozzle construction according to claim 1, said subpiston includingan enlargement on its rear end defining said forwardly facingeifective-pressure-area surface, said first-named piston being providedwith a rear chamber slidably receiving said subpiston enlargement, andsaid subpiston being formed with a longitudinally extending throughpassage for conducting leakage fluid from said chamber outward throughsaid orifice.

3. A nozzle construction according to claim 2, said additional resilientmeans being located in said chamber in bearing engagement with saidsubpiston enlargement.

4. A nozzle construction comprising a generally cylindrical housinghaving a closed forward end provided with a discharge orifice, aninternal annular forwardly facing shoulder in said housing spaced fromthe forward housing end, an annular internal rearwardly facing shoulderspaced intermediate the forward housing end and said forwardly facingshoulder and in facing relation with the latter to define therebetweenan internal annular groove, a piston slidable in said housing having onits forward side an enlarged head located between said shoulder andforward housing end and movable into and out of seating engagement withsaid shoulder, said piston being provided with external longitudinallyextending grooves defining fluid-passage means communicating betweenopposite sides of said piston when said piston head is out of saidseating engagement, said passage means being closed when said pistonhead is in said seating engagement, said groove serving as a preliminaryswirl chamber for fluid passing forwardly through said passage means toeffectively swirl and atomize fluid at relatively low flow rates, andresilient means operatively connected between said housing and piston tobias the latter rearward and urge said piston head into said seatingengagement, said resilient means being of a strength such that a desiredfluid pressure on the rear side of said piston unseats said piston headand opens said passage means.

5. A nozzle construction according to claim 4, said forwardly facingshoulder having an internal corner of substantially degrees on itsforwardly facing side, and said piston head having a rearwardly facingsurface combining with the rearwardly adjacent external surface of saidpiston to define an angle of substantially 90 degrees, for nonfrictionalmating engagement of the rearwardly facing head surface with saidforwardly facing shoulder.

6. A nozzle construction according to claim 4, said housing comprising agenerally cylindrical outer housing shell having an internal axialrearwardly facing taper, and an inner housing shell engaged in saidouter housing shell and having an external axial forwardly facing taperin abutting engagement with the taper of said outer shell, to therebyinsure proper axial alignment of said inner and outer housing shellswithout excessively close manufacturing tolerances.

References Cited in the file of this patent UNITED STATES PATENTS2,349,221 Gorrie May 16, 1944 2,572,606 Fisher Oct. 23, 1951 2,801,881Campbell Aug. 6, 1957

